/**
 * Keafmd
 *
 * @ClassName: Demo6
 * @Description: Demo6
 * @author: lijl
 * @date: 2022/12/11 14:35
 * @Blog: https://keafmd.blog.csdn.net/
 */
interface IShape{
    double area();
}
class square implements IShape{
    private double length ;
    public square(double length){
        this.length = length;
    }
    public double area(){
        return length*length;
    }
}
public class Demo6 {
    public static void main(String[] args) {
        square s = new square(6);
        System.out.println(s.area());
    }
}
